An intermittent or repeating alarm clock rings and stops periodically instead of ringing steadily. Several American clock companies introduced them in the 1900s.
Westclox introduced the “Alternating” alarm clock in 1904, and applied for a patent in 1906. The U.S. Patent Office issued the patent on June 4, 1907. Quoting from it “My invention relates to an improvement in ‘repeating alarm clocks,’ wherein after the alarm has tripped in the usual manner employed in ordinary alarm clocks, the alarm is sounded intermittently and thus made more effective, as it is shown by experience that it is the starting of the alarm and not the continuous ringing which awakens the sleeper.”
Below are the patent’s illustrations:
“On the shaft of third wheel 5 is fastened a cam 6, which has a series of tripping points 7 pressed out of the side of its periphery as shown in figures III and IV. These tripping points 7 engage with a projection 8 of a spring 9, one end of which is fastened to the front movement plate 1 by means of the pillar screw 24. The other end 10 of spring 9 is formed into a projection from said spring 9 which moves into the path of the hammer lock 11 and locks same whenever the projection 8 from said spring 9 passes between the tripping points 7 of the cam 6. Said projection 10 of spring 9 is out of the path of the hammer lock 11, leaving the hammer 14 free to vibrate whenever projection 8 of said spring 9 is riding on the tripping points, or the parts of the cam lobes 7 which lie in the plane of the cam 6.”
The first drawing shows alarm escape wheel (part 15) to the left of the movement plates (not within the plates)! The movement photo below shows that the clock was actually made this way, with a riveted extension on the front and back plates to hold the alarm escape wheel. By doing this, standard production movement plates did not need much, if any, change.
The alarm mainspring is open (no barrel), contrary to most Westclox clocks of the time. The time gears, spring click, mainspring, balance, etc. are just like an America alarm clock of the same period. Westclox discontinued the Alternating alarm clock in 1920.
The famous Big Ben alarm clock, developed in 1908 and introduced to the market in 1910, has a more refined intermittent mechanism, and its alarm has a “Steady” and “Repeat” mode. A patent issued November 17, 1908 covers the Big Ben movement including its repeat mechanism. A patent issued May 24, 1910 shows an improved repeat mechanism. The repeat lever design evolved in the first several years of Big Ben production.
Bingo style 1, made from 1914 to 1923, is a cost reduced Big Ben with the same overall appearance, but slightly smaller. Its movement is rear-mounting like the Big Ben style 1a, and the dial has numerals like the very early Big Ben style (notice the backwards curve on the numeral 7). The legs are double hexagon like the first Big Ben style 1a clocks. The alarm is always in “Repeat” mode.
See my Big Ben and Baby Ben Identification Guide for more information.
The Westclox Sleep Meter Intermittent (1914 to 1920) and Westclox Bunkie (1920 to 1925) are repeating alarm clocks. (Sleep Meter Intermittent received the new name Bunkie in 1920). The movement has a solid back plate (no removable mainspring barrels) to cut cost compared to the Big Ben movement. The case is seamless nickel-plated brass.
A winding barrel like Big Ben’s time barrel encloses the alarm mainspring and time mainspring of the Bunkie and Sleep Meter Intermittent. The repeat cam is like that of a Big Ben, the pivoted repeat lever is similar to a Big Ben’s. As the third wheel rotates, its cam pushes on a pin on the repeat lever, raising it. The other end of the lever moves out of the path of a tail on the alarm hammer, allowing the alarm to ring. When the third wheel rotates further and the pin falls off a point on the cam, the repeat lever blocks the tail of the alarm hammer.
This has been an overview of the first Westclox repeating or intermittent alarm clocks. The intermittent feature continues in the Big Ben “Loud Alarm” (1935 and on), but the alarm is always in “Repeat” mode. Westclox discontinued making the Loud Alarm in 1956. In the 1970s Westclox made Style 8 Big Ben Repeater and Baby Ben Repeater alarm clocks.
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